This study proposes to enroll approximately 1100 Rwanan men in a four- year prospective cohort study on the epidemiology of HIV (human immunodeficiency virus) infection and risk behaviors. Study subjects will be the husbands or primary sexual partners of 1469 women already participating in an ongoing cohort study HIV infection among women ages 20-37 in Kigali, the capital of Rwanda. This study will employ cross-sectional analyses using interview-administered questionnalres and HIV antibody testing at baseline, with followup assessments every 6 months for four years. The study will assess prevalence and correlates of HIV seropositivity and high iisk behavior among these men. It will examine rates and predictors of behavior change among subjects, and of seroconversion among those men who are initially seronegative. An educational video about HIV, AIDS, and high risk behavior will be produced in the local language, will be directed specifically towards men, and will be culturally sensitive. Study subjects will view this video during enrollment, and further education will be provided by trained Rwandan health personnel through didactic sessions and group discussions. Subjects will be offered condoms (preferably) or spermicides as a means of reducing the risk of HIV infection. Variables that are associated with accepting and using one of these methods will be identified, and the impact method use on seroconversion will be determined. A study of approximately 125 discordant couples (in which only one partner is infected with HIV--half of these involve women) will also be performed. The male partners in these couples will be idendfied as a subset of the male cohert; the female partners are enrolled in the women's cohort study which is already underway. These couples will be evaluated every 3 months for the incidence and predictors of behavior change and seroconversion. Men in Rwanda control sexual decision-making and, unlike most Rwandan women, usually have multiple partners. Preventing further transmission of HIV requires increased awareness and behavioral change among these men. This study, with the existing Rwandan women's study, will provide a comprehensive examination of the rates of infection and high risk behavior in urban Rwanda, with implications for developing improved prevention programs in Rwanda, in other African nations, and in the rest of the world.